December was the month of the rise and fall of Newt Gingrich. Herman Cain was already on the decline, paving the way for Gingrich to become the next Anti-Romney flavor of the month. Most of Cain's support was shifting over to Gingrich. On December 3, Herman Cain dropped out, falling under the weight of yet another sex scandal.

Gingrich's rise took place as quickly as Cain's and Rick Perry's had. Gingrich had become the greatest threat to Romney's candidacy since Perry. But unlike Cain and Perry, Gingrich was able to use his intellect and rhetorical skill to push his numbers higher than those of his predecessors. Rather than collapsing in the debates, Gingrich impressed the audience. In both of the month's debates, on December 10 and December 15, Gingrich was widely proclaimed the winner. While Romney performed ably in the December 15th debate, he made a gaffe in the prior debate when he offered Perry a $10,000 bet.

Gingrich reached his peak around December 13, when he nearly tied Mitt Romney on Intrade. Intrade investors, like the Republican establishment, were skeptical of Gingrich, but his poll numbers washed the skepticism away: Gingrich took a double-digit lead over all his opponents in the national polls, a double-digit lead in Iowa, a lead of about 20 points in South Carolina, and dominated Florida polls by polling at nearly 50%. Even Romney's New Hampshire stronghold buckled, reducing Romney's lead to 10-15 points in some polls.

Notwithstanding Gingrich's performance at the December 15th debate, the tide began to turn against him in mid-December. Romney's campaign, which had shied away from the attacks and negative ads that characterized it in the 2008 primary, understood that it was time to unload. In early December, Romney released a torrent of attack ads against Gingrich, mostly in Iowa. Ron Paul, too, began to spend from his online money chest to attack Gingrich. Even Perry, at long last, realized that he needed to focus on winning the Anti-Romney vote, and shifted his attacks in Gingrich's direction.

It was too much for Gingrich to bear. He had little money to spend on ads of his own to counter the attacks. But what really eroded Gingrich's support was the fact that the ads were based in truth: Gingrich was not the pure, Tea Party-friendly conservative that he pretended to be. Since Gingrich didn't have an advantage in conservatism, there was no counterweight to his baggage and electability concerns. Gingrich steadily fell in the polls, particularly the national and Iowa polls.

By the end of the month, the media increasingly focused on Iowa. With Gingrich (mostly) out of the way there, Romney took a slight lead over Paul, who somehow managed to translate dollars to poll numbers. Rick Santorum, who faithfully waited his turn as the final Anti-Romney, got a last-minute increase in Iowa polls. With the Iowa Caucus just a few days away, polls essentially suggested a three-way tie among Romney, Paul, and Santorum, with the late momentum on Santorum's side. Perry and Michele Bachmann, who placed most (or all) of their hopes on Iowa, were too far behind to hope for a win. Gingrich was left somewhere in between, hoping that a loss in Iowa wouldn't jeopardize his leads in South Carolina and Florida.